Two cell lines cloned from a culture of Buffalo rat embryonic cells transformed by Herpes virus differ in their oncogenicity and immunogenicity. The G2 cell line is less oncogenic and more immunogenic than the RGS cells. We will evaluate the presence of tumor associated antigens on the surface of these different transformed cells. Further studies will be done to modify the presence or presentation of these membrane antigens, to determine their effects on oncogenicity, and immunogenicity, and the effectiveness of these modifications in preventing the development of tumor or treatment of existing tumor burdens. Adoptive transfer experiments using cytoxic lymphocytes will be undertaken to modify the course of existing tumors. Modification of the elaboration of an immunosuppressive substance will be studied to determine what effect this has on tumor growth.